The ASTROCULTURE(trademark) plant growth unit flown as part on the STS-63 mission in February 1995, represented the first time plants were flown in microgravity in a enclosed controlled environment plant growth facility. In addition to control of the major environmental parameters, nutrients were provided to the plants with the ZEOPONICS system developed by NASA Johnson Space Center scientists. Two plant species were included in this space experiment, dwarf wheat (Triticum aestivum) and a unique mustard called "Wisconsin Fast Plants" (Brassica rapa). Extensive post-flight analyses have been performed on the plant material and it has been concluded that plant growth and development was normal during the period the plants were in the microgravity environment of space. However, adequate plant growth and development control data were not available for direct comparisons of plant responses to the microgravity environment with those of plants grown at 1 g. Such data would allow for a more complete interpretation of the extent that microgravity affects plant growth and development

Bula, R. J.

English

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FINAL REPORT
for
Research Grant
NAG 9-851
LYNDON B. JOHNSON SPACE CENTER
PLANT GROWTH AND DEVELOPMENT IN THE ASTROCULTURE TM
SPACE-BASED GROWTH UNIT - GROUND BASED EXPERIMENTS
R.J. BULA
WISCONSIN CENTER FOR SPACE AUTOMATION AND ROBOTICS
UNIVERSITY OF WISCONSIN-MADISON
FEBRUARY 17, 1997
INTRODUCTION
The ASTROCULTURE TM plant growth unit flown as part on the STS-63 mission in
February 1995, represented the first time plants were flown in microgravity in a enclosed
controlled environment plant growth facility. In addition to control of the major
environmental parameters, nutrients were provided to the plants with the ZEOPONICS
system developed by NASA Johnson Space Center scientists. Two plant species were
included in this space experiment, dwarf wheat (Triticum aestivum) and a unique mustard
called "Wisconsin Fast Plants" (Brassica rapa). Extensive post-flight analyses have been
performed on the plant material and it has been concluded that plant growth and
development was normal during the period the plants were in the microgravity environment
of space. However, adequate plant growth and development control data were not
available for direct comparisons of plant responses to the microgravity environment with
those of plants grown at 1g. Such data would allow for a more complete interpretation of
the extent that microgravity affects plant growth and development.
OBJECTIVES
The objective of the experiments was to provide ground-based plant growth and
development data to serve as control information for comparison with post-flight data
collected on the plant material recovered from the ASTROCULTURE TM flight unit
following the STS-63 mission.
EXPERIMENTAL PROCEDURES
The experiments involved providing plant material for analyses following three growth
periods at 1 g conditions. The first was a growth period that duplicated the growth period
of the STS-63 mission and at the experiment defined environmental conditions. The
second growth period involved the growth period of the STS-63 mission but at the
environmental conditions recorded during the STS-63 mission. The third growth period
involved growing the plants at the experiment defined conditions and terminating this
growth period at the time period equivalent to the time STS-63 was launched. This last
growth period would provide an assessment of the status of the plants at time of launch.
For the first growth period (to provide ground control plant material), seeds of the
Wisconsin Fast plants were planted in the root module of the ASTROCULTURE TM flight
unit that translated into a growth period of 5, 12, 20, and 25 days prior to what was
https://ntrs.nasa.gov/search.jsp?R=19970041269 2020-06-16T01:33:43+00:00Z
consideredto be thetimetheflight unit was turnedover for installationinto the orbiter.
This plantingsequenceprovidedplantsat different stagesof maturityduring the space
flight. Fourseedswereplantedat five intervalsin arowof therootmodule. After5 days,
the seedlingswerethinnedto a singleplantat eachsite. Thefirst seedingtook placeon
January2, 1996andtheotherseedingdatesatthetimesdefined.
Wheatseedswereplantedat 4 daysprior to thedefined turn over time. Ten seeds were
place in each of 2 rows of the root tray. The wheat seeds were planted on January 23,
1996.
A complete sequence of planting, turnover, and harvest dates of this first growth period
experiment is provided in Table 1.
Table 1. Schedule of planting and harvest activities of the experiment to
determine plant growth and development at lg conditions for comparison
with plant growth and development in microgravity during the STS-63
mission.
30 January, 1996
4 February
12 February
19 February
20 February
24 February
28 February
6 March 1996
12:00 Noon
12:00 Noon
12:00 Noon
12:00 Noon
12:00 Noon
12:00 Noon
12:30 AM
2:00 PM Harvest
Plant 1 row of Fast Plants, 25 days prior to turnover
Plant 1 row of Fast Plants, 20 days prior to turnover
Plant 1 row of Fast Plants, 12 days prior to turnover
Plant 1 row of Fast Plants, 5 days prior to turnover
Plant 2 rows of wheat, 4 days prior to turnover
Turnover of ASC hardware, Noon, 31 January, 1995
Launch of STS-63, 3 February, 1995
Equivalent to return of hardware at end of mission,
11 February, 1995.
The root module with the seeded material was maintained in a controlled environment
chamber until turn over time. Environmental conditions of the growth chamber were
defined by the experiment as: 200 (+20) _tmolm-2s ' of continuous light (no dark period),
24 (+2) °C temperature of the air in the plant chamber, 65 (+ 10) % relative humidity of the
air in the plant chamber, and 0.5 kPa water delivery loop pressure. No carbon dioxide
control was available in the plant growth chamber during the growth period. In the
ASTROCULTURE TM flight unit, atmospheric carbon dioxide concentration was controlled
at 500 ppm by addition of pure carbon dioxide when the concentration was below 450
ppm.
At 36 hours before the scheduled launch time, the rooting module with the plants was
removed from the controlled environment plant chamber and installed in the
ASTROCULTURE TM flight unit. The plants were then grown in the ASTROCULTURE TM
flight unit for a time period equivalent to the time the shuttle was on the launch pad,
duration of the mission, and the time from landing of the orbiter to the recovery of the flight
unit. The launch of STS-63 was delayed 24 hours and this resulted in the plants being in
the orbiter for a period of 60 hours prior to being launched into space.
The secondexperimentincludedtheplantmaterialdescribedfor the first experimentand
grown in the controlledplantenvironmentchamberunderthe environmentalconditions
describedfor the first experiment. Following installationof the root module in the
ASTROCULTURETM flight unit, the light intensity, air temperature, relative humidity of
the air, carbon dioxide concentration, and water delivery loop pressure of the plant chamber
in the ASTROCULTURE TM flight unit were controlled at levels that simulated the
conditions as recorded during the STS-63 mission rather than at the experiment defined
levels. The light levels in the plant chamber recorded during the STS-63 mission are
shown in Fig. 1. The air temperatures in the plant chamber recorded during the STS-63
mission are shown in Fig. 2. The percent relative humidity of the air in the plant chamber
recorded during the STS-63 mission is shown in Fig. 3. The concentration of carbon
dioxide in the plant chamber air during the STS-63 mission is shown in Fig. 4. The water
delivery loop pressure of the plant chamber during the STS-63 mission is shown in Fig. 5.
250
200
0
O
E tso
_ 100
o_
b-I 50
I I I I I I J ! I I I I P P q I I I I I I I I I I I i I I I J I I q I I
- _ _ _ - _ ,_
Experiment elapsed time, minutes
Figure 1. Light intensity in the plant chamber of the ASTROCULTURE TM flight unit during the
STS-63 mission.
A complete sequence of planting, turnover, and harvest dates of this second growth period
experiment is provided in Table 2.
The third experiment included the plant material described for the first experiment and
grown in the controlled plant environment chamber under the environmental conditions
described for the first experiment. Rather than installing the root module with the plants
into the ASTROCULTURE TM flight unit, the root module was left in the controlled
environment plant chamber for an additional 60 hours and then harvested. These plants
represented the condition of the plants at the time the STS-63 mission was launched, which
was delayed for 24 hours and the plants were in a 1 g environment while on the launch pad
in the orbiter.
40.0
35.0
30.0
_ 25.0
20.0
15.0
.t,
.< 10.0
5.0
0.0 [ I I I I , I I ] I 1 ] 1 I I I [ I [ I [ I I I I [ I I [ ] I r i [ I [ I I ', ', I I
Experiment elapsed time, minutes
Figure 2. Air temperature in the plant chamber of the ASTROCULTURE TM flight unit during the
STS-63 mission.
.. 100.0
90.0
80.0
"" 70.0
60.0
50.0
-- 40.0
30.0
20.0
10.0
0.0
Experiment Elapsed time, minutes
Figure 3. Atmospheric relative humidity in the plant chamber of the ASTROCULTURE TM
flight unit during the STS-63 mission.
4
4O00
35OO
30oo
2500
! 2000
._ 1500
_g_ 1000
A_ 500
trument failure
Experiment elapsed time, minutes
Figure 4. Concentration of carbon dioxide in the air of the plant chamber in the
ASTROCULTURE TM flight unit during the STS-63 mission.
4.00
2.00
¢ff
o.oo
-2.oo
-4.00
t_.
-6.00
"g3
t. -8.00
_: -lO._
I
gg _g _
Experiment Elapsed time, minutes
Figure 5. Water delivery loop pressure, cm of water column, of the root module of the plant
chambers of the ASTROCULTURE TM flight unit during the STS-63 mission.
Table 2. Schedule of planting and harvest activities of the experiment to
determine plant growth and development under environmental conditions
that simulated those that were recorded in the plant chamber of the
ASTROCULTURE TM flight unit during
7 November, 1996 8:00 AM Plant
12 November 8:00 AM Plant
20 November 8:00 AM Plant
27 November 8:00 AM Plant
28 November 8:00 AM
2 December 8:00 AM
6 December 12:30 AM
13 December 1996 10:00AM
the STS-63 mission.
1 row of Fast Plants, 25 days prior to turnover
1 row of Fast Plants, 20 days prior to turnover
1 row of Fast Plants, 12 days prior to turnover
1 row of Fast Plants, 5 days prior to turnover
Plant 2 rows of wheat, 4 days prior to turnover
Turnover of ASC hardware, Noon, 31 January, 1995
Launch of STS-63, 3 February, 1995
Harvest - Equivalent to return of hardware at end of
mission, 11 February, 1995.
A complete sequence of planting, turnover, and harvest dates of this second growth period
experiment is provided in Table 3.
Table 3. Schedule of planting and harvest activities of the experiment to
define the condition of the plants at the time the shuttle was launched since
the STS-63 mission launch time was delayed 24 hours.
15 November, 1996 12:30AM
20 November 12:30 AM
28 November 12:30 AM
5 December 12:30 AM
6 December 12:30 AM
10 December 12:30 AM
12 December 12:30 PM
Plant 1 row of Fast Plants, 25 days prior to turnover
Plant 1 row of Fast Plants, 20 days prior to turnover
Plant 1 row of Fast Plants, 12 days prior to turnover
Plant 1 row of Fast Plants, 5 days prior to turnover
Plant 2 rows of wheat, 4 days prior to turnover
Turnover of ASC hardware, Noon, 31 January
Harvest - Equivalent to launch of STS-63 @ 12:30
AM, 3 February, 1995.
RESULTS
The conduct of the plant growth experiments was delayed in response to scheduling of
availability of NASA Johnson Space Center scientists that were responsible for harvesting
the plant material and processing it for further analyses. Thus, the first experiment growth
period was from January 30, 1996 to March 6, 1996. The second and third plant growth
experiments were conducted during the period of November 7, 1996 to December 13,
1996. As was defined in the Grant Statement of Work, harvesting the plants and the
6
analysesof the plant materialwas the responsibilityof NASA Johnson Space Center
personnel. Plant data relative to the plants based on fresh conditions was completed by
NASA Johnson Space Center personnel at the University of Wisconsin-Madison at time of
harvest. Also, at this site, preservation of the plant material for subsequent analyses was
accomplished by NASA Johnson Space Center personnel and shipped to the Johnson
Space Center where the analyses were to be performed.
In general, the plants grown under 1 g conditions in these ground-based experiments were
similar to the plants grown in a microgravity environment during the STS-63 mission. It
may be worthwhile to point out that the environmental conditions in the plant chamber of
the ASTROCULTURE TM flight unit deviated from the experiment defined environmental
conditions. The mustard or Fast Plants from the ground-based experiment that simulated
the environmental condition recorded during the STS-63 mission exhibited more
deterioration due to high air temperatures and relative humidity compared to the mustard or
Fast Plants grown in microgravity during the STS-63 mission. This may be due to more
extensive condensation of the humidity on the plant material under 1 g conditions compared
to what may have occurred in microgravity. The wheat plants did not exhibit such
deterioration and appeared similar to the plants grown in microgravity, even under the
environmental conditions that deviated from the experiment defined set points.
SUMMARY
Three ground-based plant growth experiments were conducted to obtain data for comparing
the growth of a mustard called Wisconsin Fast Plants and wheat in microgravity during the
STS-63 mission. The three experiments represented a simulation of the experiment
conducted during the STS-63 mission with the environmental conditions in the plant
chamer in the ASTROCULTURE TM flight unit controlled at the experiment defined level,
the same experiment except the environmental conditions in the plant chamber were
controlled to reflect the environmental conditions as recorded during the STS-63 mission,
and an experiment to define the condition of the plants at the time the STS-63 mission was
launched.
The plants were harvested at the scheduled dates and the desired data collected on the fresh
plant material. Plant material was also preserved for subsequent analyses. The data
describing the plant growth during these experiments are being developed and summarized
by Johnson Space Center scientists.


Plant Growth and Development in the ASTROCULTURE(trademark) Space-Based Growth Unit-Ground Based Experiments

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